This invention relates generally to the field of orthopedic medicine and more specifically to the design of an improved medical bandaging product and material which includes a warp knitted, double-layered fabric substrate, a method for constructing such an improved bandaging product, and a method of constructing and applying an improved bandaging product.
Medical bandages for use in the treatment of injuries, such as broken bones requiring immobilization of a body member, are generally formed from a strip of fabric or scrim material impregnated with a substance which hardens into a rigid structure after the strip has been wrapped around the body member. The hardening substance traditionally used in carrying out this procedure is plaster-of-paris.
Conventional practice has been to fabricate a cast or splint upon an injured limb by initially applying to the limb a protective covering of a cotton fabric or the like and then overwrapping the covering and limb with a woven cloth impregnated with plaster-of-paris which has been wetted by dipping in water immediately prior to application. This practice is still in widespread use but possesses several significant disadvantages. For example, the above-described application procedure is messy and time consuming. Several components are required and considerable skill is necessary.
In order to alleviate the above-recited disadvantages of the conventional application procedure for plaster-of-paris casts and splints, unitary splinting materials have been devised and are disclosed in, for example, U.S. Pat. Nos. 3,900,024, 3,923,049, and 4,235,228. All of these patents describe a padding material with a plurality of layers of plaster-of-paris impregnated cloth. Such unitary splinting materials are not as messy and can be applied more quickly but still suffer from a number of disadvantages inherent in plaster-of-paris cast materials. All plaster-of-paris splints have a relatively low strength to weight ratio which results in a finished splint which is very heavy and bulky. Plaster-of-paris splints are slow to harden, requiring 24 to 72 hours to reach maximum strength. Since plaster-of-paris breaks down in water, bathing and showering are difficult. Even if wetting due to these causes can be avoided, perspiration over an extended period of time can break down the plaster-of-paris and create a significant problem with odor and itching.
A significant advance in the art of casting and splinting is disclosed in U.S. Pat. Nos. 4,411,262 and 4,502,479. The casting materials disclosed in these patents include bandaging materials which incorporate a substrate formed from a plurality of flexible fabric layers, such as fiberglass, impregnated with a moisture-curing resin. These bandaging materials are enclosed in a moisture-free, moisture-impervious package until use. Compared to plaster-of-paris, these products are extremely lightweight, have a very high strength to weight ratio and can be made relatively porous, permitting a flow of air through the casting material. However, no provision has been made for moisture-curing systems which incorporate a substrate which is formed from a single layer of fabric, yet is strong and absorbent enough to be impregnated with amounts of moisture-curing resin comparable to those amounts absorbed by conventional multi-layered substrates.
U.S. Pat. Nos. 4,770,299 and 5,003,970, among others owned by applicant, each disclose roll-form synthetic bandaging products which include the ability to dispense desired lengths of bandaging material when needed, while sealing the remaining length of material for later use. Similar products are also sold in precut lengths sealed in a single use, moisture-impervious envelope. Although these products have proven to be very successful in many applications, each product is formed using multi-layered substrate materials.
Both the conventional plaster-of-paris casting method and the more recent moisture-curable resin casting method possess certain disadvantages. Plaster-of-paris casts are bulky, heavy and difficult to apply. Even though moisture-curable resin bandage products are lightweight, durable and relatively easy to apply, such products remain relatively expensive to produce.
This invention combines the advantages of both plaster-of-paris and moisture-curable resin systems while avoiding their respective disadvantages. This is accomplished by providing a unitary splinting system which incorporates moisture-curable resin materials formed from a resin-impregnated substrate having both a lighter weight and improved strength. Unlike prior art resin systems which employ multiple layers of resin-impregnated substrate layers, the resin system of the present invention takes advantage of a single layer of warp-knitted fabric. This unique substrate fabric employs a continuous inlaid stitch. This results in a double-knitted fabric which has a lighter weight, yet retains the absorption capabilities of multi-layered substrates. Using a single layer of double-knitted fabric in the substrate further results in reduced production and labor costs in comparison with other synthetic cast products. For example, assembly of prior art, multi-layered substrates requires placement of the overlying fabric layers of the substrate by hand, which is a time consuming process. To ensure that the fabric layers do not separate, the layers must then be stitched together by running one or more seams along the entire length of the substrate. Use of a substrate having only one layer eliminates these labor-intensive layering and stitching steps, and results in a bandaging product which is more cost effective to produce.
Eliminating the multi-layered substrate structure also eliminates the rough, uneven edges present on prior art cured substrates. Such frayed edges are commonplace in prior art bandaging products having multi-layered substrates, and materialize after the resin in such substrates undergoes final curing. These rough edges cause irritation and damage to the skin of the patient upon whom the bandage is ultimately applied. In contrast, the substrate of the present invention has uniform side edges which result from using the single-layer of double-knitted fabric, rather than multiple, uneven fabric layers. This novel structure results in a medical bandage product having a moisture-curable substrate which is lighter in weight than conventional products, yet is stronger and more cost-effective to produce.